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Kitkat1

  • one year ago

A pencil at a stationery store costs $1, and a pen costs $1.50. Stella spent $21 at the store. She bought a total of 18 items. Which system of equations can be used to find the number of pencils (x) and pens (y) she bought? (5 points) 1.5x + y = 21 x = 18y 18x + y = 21 x = 1.5y x + 1.5y = 21 x + y = 18 x + 18y = 21 x = 1.5y

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  1. Kitkat1
    • one year ago
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    Medals!

  2. whpalmer4
    • one year ago
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    Okay, if a pencil costs $1, and \(x\) represents the number of pencils, how do you write an expression for the amount of money spent on pencils?

  3. Kitkat1
    • one year ago
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    i think like the 3rd answer

  4. whpalmer4
    • one year ago
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    well, let's figure it out. how do you write the expression for the amount spent on pencils, if a pencil costs $1 and there are \(x\) pencils?

  5. Kitkat1
    • one year ago
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    Idk

  6. whpalmer4
    • one year ago
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    what is the cost of 1 pencil?

  7. Kitkat1
    • one year ago
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    1$

  8. whpalmer4
    • one year ago
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    what is the cost of 2 pencils?

  9. Kitkat1
    • one year ago
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    2$

  10. whpalmer4
    • one year ago
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    what is the cost of 57 pencils? (btw, the $ goes in front)

  11. whpalmer4
    • one year ago
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    you get the cost by multiplying the cost of 1 item by the number of items, right?

  12. Kitkat1
    • one year ago
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    $57

  13. Kitkat1
    • one year ago
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    Im pretty sure the answer is the 3rd one

  14. whpalmer4
    • one year ago
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    so the cost of \(x\) pencils when pencils cost $1 each is \(\$1*x\) or \(1x\) or \(x\) if we assume the price is in dollars. Pens cost $1.50 each. If you have \(y\) pens, how much is that?

  15. Kitkat1
    • one year ago
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    1.5y

  16. whpalmer4
    • one year ago
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    I agree the answer is C: I'm trying to solidify your understanding of this so you never have to ask again, you'll just know the right answer. Worth a minute or two of your time, right? Yes, 1.5y is the expression for the cost of the pens. We know that we spent $21 on \(x\) pencils and \(y\) pens, so how do we write that in an equation?

  17. Kitkat1
    • one year ago
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    x + 1.5y=21

  18. whpalmer4
    • one year ago
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    Very good. And if we know that we have a total of 18 items, how do we write that?

  19. Kitkat1
    • one year ago
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    x + y = 18

  20. Kitkat1
    • one year ago
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    Can u help me with one more?

  21. whpalmer4
    • one year ago
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    Excellent. For a medal of your own, how many pens and pencils?

  22. Kitkat1
    • one year ago
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    18 and 21

  23. Kitkat1
    • one year ago
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    The equation 2.2x – 4.4 = 1.8x can be transformed to form which of the following expressions? 4.0x = 4.4 0.4x = –4.4 0.4x = 4.4 4.0x = –4.4 Can u help me with this one?

  24. whpalmer4
    • one year ago
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    No, 18 pens and 21 pencils doesn't add up to 18 items, does it?

  25. Kitkat1
    • one year ago
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    31

  26. whpalmer4
    • one year ago
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    Come on, you aren't thinking. The total number of pens + pencils is 18. The total cost is $21. Well, whatever. Let's do your other problem. \[2.2x – 4.4 = 1.8x\] What happens if you subtract \(1.8x\) from both sides?

  27. Kitkat1
    • one year ago
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    2.2x - 2.6

  28. Kitkat1
    • one year ago
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    Now what?

  29. Kitkat1
    • one year ago
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    so 0.4x in the beginning

  30. whpalmer4
    • one year ago
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    \[2.2x-4.4-1.8x=1.8x-1.8x\]\[2.2x-1.8x-4.4 = 0x\]\[0.4x-4.4=0\] Now we add 4.4 to both sides: \[0.4x-4.4+4.4=0+4.4\]\[0.4x=4.4\]

  31. Kitkat1
    • one year ago
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    Thank you!

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